1. Field of the Invention
The present invention relates to an image recording apparatus configured to record images while reciprocating a recording head with a carriage, and more particularly to an image recording apparatus in which drive power of a plurality of drive sources is transmitted to a plurality of driven portions
2. Description of the Related Art
There is conventionally known an ink-jet printer as an image recording apparatus in which ink is ejected on the basis of input signals to record images on a recording medium such as a recording sheet. The ink-jet printer is configured so as to introduce ink into an actuator of a recording head and eject, onto the recording sheet, the ink pressurized by utilizing deflection or flexure of piezoelectric elements, electrostrictive elements, and so on or by utilizing local or partial boiling of the ink by heat-generating elements, based on input signals.
In the ink-jet printer, when the recording sheet is fed onto a sheet-discharge tray from a sheet-supply tray, an image recording operation is performed in which the ink is selectivley ejected onto the recording sheet from the recording head. A sheet-supply operation in which the recording sheet is supplied from the sheet-supply tray to a sheet-feed path, and a sheet-feed operation in which the recording sheet is fed in the sheet-feed path are performed by rotations of rollers referred to as a sheet-supply roller and a sheet-feed roller in a state in which the rollers are pressed on the recording sheet. As the drive source of the rollers each as one of driven portions, a motor such as a DC motor or a stepping motor is used. Drive power is transmitted from the motor to the rollers by a drive-power transmitting system including a pinion gear, a timing belt, and so on.
In the image recording operation, air bubbles may be generated in nozzles of the recording head through which the ink is ejected, or the nozzles may be plugged or clogged with foreign matters, whereby an ink ejection failure may occur. As a technique for restoring or preventing the ink ejection failure, there has been known what is called a purging operation that is a technique for removing, by sucking, the air bubbles and the foreign matters from the nozzles of the recording head. A maintenance unit for performing the purging operation includes a cap for covering the nozzles of recording head, a pump for reducing a pressure in the cap, and so on. The motor is also used as a drive source for driving the pump, as one of the driven portions, of the maintenance unit and a cam, as another of the driven portions, for switching a state of an air-discharge valve. The drive power is transmitted from the motor to a selected one or ones of the driven portions by a drive-power transmitting system like the drive-power transmitting system described above.
There is conventionally known an image recording apparatus including a switching mechanism for switching driven portions to which the drive power of the motor as the drive source is transmitted. This switching mechanism selectively transmits the drive power to a selected one or ones of the driven portions depending upon a position of the carriage, as disclosed in Japanese Patent Application Publication No. 2007-90761 (Patent Document 1). Thus, the drive power can be transmitted from one drive source to the sheet-feed roller and so on when the image recording operation is performed, or to the maintenance unit when the purging operation is performed, for example.
According to Patent Document 1, drive power of one LF motor (42) is selectively transmitted to one or ones of a plurality of driven portions by the switching mechanism (100). This switching mechanism (100) includes a switching gear (102) and four types of transmission gears, namely, a transmission gear (113) for intermittently supplying recording sheets, a transmission gear (114) for successively supplying the recording sheets, a transmission gear (121) for supplying the recording sheets accommodated in a lower cassette, and a transmission gear (115) for maintenance of the recording head. A lever (104a) is positioned at one of a first, a second, and a third guide position (111, 112, 108), whereby the switching gear (102) is meshed with a selected one of the transmission gears that corresponds to the one of the guide positions at which the lever is positioned, so as to transmit the drive power to the one of the transmission gears. A position of the lever (104a) is switched depending upon a position of a carriage (13) which is moved in a main scanning direction in correspondence with respective modes of operations of the image recording apparatus. It is noted that respective reference numerals within parentheses are reference numerals that are used in Patent Document 1.